514 University of California Publications in Zoology [Vol. 18 



reason they appear, except in side view in optical section of the living 

 miracidium, merely as ciliated holes (figs. 2, 3, /). This appearance 

 confused Holcomb (1907, p. 68) who misinterpreted them entirely. 

 Only the beginnings of the capillaries were made out. I could dis- 

 tinguish coiled tubules on each side, but could not trace their con- 

 nections. In view of the position of the excretory pores and flame 

 cells it is very probable that the excretory system in this miracidium 

 is similar to that of the miracidium of >S'. japonicum (fig. 6, 7). 



Functionally the schistosome miracidium appears to have no dorso- 

 ventral or lateral differentiation, since it is round in cross-section and 

 revolves on its long axis in locomotion. Structurally, however, this 

 differentiation is very striking. The arrangement of the excretory 

 system and cephalic glands gives a very clear bilateral symmetry. The 

 cephalic glands lie nearer one surface of the body, and the central 

 nervous body and rudimentary digestive sac lie nearer the other. 

 Since the use of the terms dorsal and ventral are meaningless for such 

 a type as this miracidium, I propose that these surfaces be designated 

 respectively the glandular and neural surfaces. The symmetry can 

 be understood most clearly by a comparison of figure 4, a lateral view 

 with figure 2, which is a view from the glandular surface, and with 

 figure 3, which is drawn from the neural surface. 



THE EGG AND MIRACIDIUM OF SCHISTOSOMA JAPONICUM 



The egg and miracidium of Schistosoma japomcutn are smaller than 

 those of S. mansoni or S. haematohium (cf. figs. 4, 6). The eggs of 

 S. japonicum from the two cases which I studied showed no trace of 

 the rudimentary spine which is so often found on the eggs of this 

 species,^ The most characteristic form of this spine is described by 

 Leiper (1911, p. 134) as follows: 



In many of the ova the spine appears to rise from the center of a slight 

 navel-like depression in the egg shell. The base of attachment is thickened in 

 all and spreads out upon the shell for a short distance in a manner somewhat 

 similar to the attachment of a thorn to the stem of a rose. 



Leiper examined about fifty eggs in all from seven different cases, 

 four in man and three in dogs, and came to the conclusion that the 

 presence of a rudimentary spine is a specific character. Katsurada 



1 In a sample of feces obtained recently from another case of Japanese 

 schistosomiasis about fifty per cent of the eggs showed no spine, while the rest 

 showed it in varying degrees of development. 



